🚀 go-pugleaf

the probability of A, given B, is the probability of A and B, divided
by the probability of B.  does anyone dare dispute me?

no? good.  to continue, let's dissect the question: "i have two children.
at least one is a daughter. what's the chance that the other is a daughter?"
is the same as "what is the chance that both of my children are female, given
that at least one is female?" so we have that A is "both of my children are
daughters", and B is "at least one of my two children is a daughter."

so the chance that both are daughters given that one is a daughter is
the chance that both are daughters AND at least one is a daughter, divided
by the chance that at least one is a daughter.

the chance that both are daughters and at least one is a daughter is
the same as the chance that both are daughters (i.e., "at least one is
a daughter" is a foregone conclusion, if both are daughters), which is
one out of four.

the chance that at least one is a daughter is one minus the chance that
both are sons, which is one minus a quarter, which is three quarters.

one quarter divided by three quarters is one third.  last i checked,
a third and a half were not the same.

to all you proponents of the so-called "common sense" argument,
remember the archaic definition of "common".

bob vesterman.